Electrical contact device having a spring acting acainst a plate for moving a plurality of contact elements



June 6, 1967 W. B. BLANK, JR 3,324,389

ELECTRICAL CONTACT DEVICE HAVING A SPRING ACTING AGAINST A PLATE EonMOVING A PLURALTTT CE CONTACT ELEMENTS Filed Sept. SO, 1965 HCI HC. E

A TTORNEYS.

United States Patent O 3,324,389 ELECTRICAL CONTACT DEVICE HAVING ASPRING ACTING AGAINST A PLATE FOR MOVlNG A PLURALITY OF CUNTACT ELE-MENTS Winfield B. Blank, Jr., Tulsa, Okla., assignor to SinclairResearch, Inc., New York, NX., a corporation of Delaware Fiieti Sept.3i), 1963, Ser. No. 312,452 4 Claims. (Cl. 324-62) This invention is anapparatus for use in a well casing or other pipe to establish anelectrical contact within the pipe. The device of this invention isuseful in, for example, corrosion determinations. In such operations aplurality of contact devices, for example, two of the units, separatedby a prearranged distance, for example, by a spacing tube, may be usedto find a difference in electrical potential between sets of two areason the inside of the casing or other pipe.

This invention is an improvement over devices of this type which a-reknown to the art in that it provides sharp contact points which canpierce thin films of oil, corrosion products, etc., within the pipe toestablish metal-to-metal contact. The contact points are spring actuatedbut are protected from wear by being kept in a retracted position duringtravel through the pipe until the position is .reached where their useis desired. The apparatus comprises a support member of a size suitablefor fitting within the pipe to be tested and retractable, sharp, contactmeans, spring actuated to engage the inside wall of the pipe whenreleased from their protected position. The .release mechanism isactuated by a change in direction of travel of the support memberthrough the pipe.

=In a preferred embodiment, the device employs contact knives, ideallythree or more of them, to center the api paratus in the pipe, and hasthe set of knives arranged in one plane perpendicular to the axis of thepipe. The spring actuation of the contact knives preferably takes placethrough a pressure plate which contacts all of the knives, transmittingspring pressure evenly to the knives. The pressure plate also serves toconduct current to and from the contact knives, whereby the current maybe conducted by the knives in parallel. Often, the knives will pivotfrom their retracted position to their extended, operable position,mounting lugs being provided on the support for this purpose.

The release mechanism preferably comprises a locking collar for theknives below the pivot points and this collar is provided with adragging mechanism which contacts the interior wall of the pipe to becontacted with the knives. Thus during the descent or other travel ofthe apparatus of the invention through the pipe the dragging mechanismserves to hold the collar, which usually is slidably mounted on thesupport tube, toward the top of the tube, and the collar holds theknives in their retracted position. The dragging mechanism may comprisea series of stiff wire cat whiskers.

The movement of the apparatus of this invention toward its testdestination is generally described in this specification and claims asdownward while movement back to the starting position is described asupward, but it will be understood that this invention may be used withhorizontally or obliquely positioned pipes, as well las those verticallypositioned.

The dragging members are so positioned on the support that they hold thecollar up, protecting the knives, during downward travel of theapparatus. When the direction of travel is reversed, the draggingmembers catch on the pipe wall or at a coupling relief sufficiently topull the locking collar down thereby releasing the knives, and enablingthe spring pressure to open them.

3,324,389 Patented June 6, 1967 A slight lowering of the mechanism thensets the knives and establishes a good electrical contact.

An important advantage of the apparatus of this invention is the paucityof parts which it employs and the simple, rugged nature of the operativeelements. The assembly may be held together by a hollow bolt and nut andthe contacting portion of the assembly is electrically insulated fromother parts.

The invention will be better understood by reference to the accompanyingdrawing which is to be considered illustrative only and not limiting.

IIn the drawing:

FIGURE l is a fragmentary cross-sectional view of the device of theinvention with the contact points in their protected position suitablefor insertion into the pipe, well-casing, etc. and

FIGURE y2 is a fragmentary cross-sectional view of the device in itsoperative or contacting position.

The apparatus comprises the support means 11, which in the embodimentshown is a cylindrical piece of tubing. This support member may beprovided with a tapered lower end 13 to facilitate entry into the pipeto be explored and also, if desired, with a tapered portion 15 at itsupper end to facilitate removal from the pipe. The support member may besuspended or otherwise transported through the pipe by means of any sortof wire line, spacing bar, sinking bar, cable, pipe, tubing etc.,directly or indirectly attached to the support member, preferably to theupper and/ or lower tapered portions 13 and/ or 15 which areelectrically insulated from the mid-section 18 of t-he support 11. Theelectrical insulation of the midsection may be brought about by anyconvenient means, for example, the washers 20 and 22 which m-ay be madeof any suitable dielectric material such as hard rubber. The upper andlower, preferably tapered, portions of the tube are fastened interiorlyto the spiders 25 and 28, respectively, through which pass the hollowbolt 30 which is provided with the hollow head 33. The nut 36 fastens tothe threaded end of the bolt 30 to hold the apparatus together. The bolt30 and nut 36 are electrically insulated by the dielectric sleeve 39 andthe upper and lower dielectric washers 42 and 44.

At the upper portion of mid-section 18 the fixed washer 46 and theslidable washer or pressure plate 48 define the spring chamber 50 whichcontains the spring 52. Fastened to the outside of the mid-section 18are three or more lugs 55 and next to each lug is a slot 58 whichpenetrates the tube. Fastened to each lug by means of the pivot 60 is aknife 63 which has an internal portion 66 and an external portion 68,which portion is usually at an angle to the interior portion 66 andwhich ends in the point 70. The mid-section 18 is provided externallyand below the lugs with the locking collar 72 which is slidably mountedon the tube, for example, by means of spring biased detent means, i.e.the ball bearings 75 which are biased by the springs 77 which operate inthe spring chambers S0. The spring chambers 80 may conveniently beformed by a circular depression in the Wall of an upper portion ofmid-section 1S.

The collar 72 is provided near its lower end with a plurality ofdragging means, for example, the piano wire cat whiskers 82. It will beobserved that the collar is of a size suiiicient to allow clearance forthe external portion 68 of each knife 63 between the collar and thetube. 'I'he upper portion of the collar 72 may be provided with theshroud 84 which is slotted to provide for entry of the portions 68, andwhich serves to prevent the apparatus from hanging up on obstructions inthe pipe. Preferably the collar is provided with a taper S8 .at itslower portion and the mid-section 18 is provided with the projections 90preferably at its lowermost periphery. These projections may be, forexample, merely screws threaded into the mid-section 18. The knives 63,as well as the detent 80, act as stops for upward travel of the collar,and the friction developed between the interior of the collar and theoutwardly spring-biased portions 68 will insure prevention of too greatupward travel of the collar 72 when the knives are in the retractedposition even if the springs 77 should fail.

An electrical lead 93 is fastened to any portion of the device which isin electrical connection with the points 70, preferably the washer 46.Another electrical lead, 96, may pass through the hollow bolt 30, forexample, to another similar apparatus located farther in the pipe 99.The line through the bolt may be insulated, although the insulatingsleeve 39 will usually serve to prevent short circuiting.

The operation of the apparatus is fairly apparent from the drawing.During entrance to the pipe or casing the knives are held in a closedposition by the locking collar. The drag of the cat whiskers against thewall of the pipe or casing aids in ykeeping the knives in theinoperative position with the points protected.

After the testing position has been reached, the apparatus is given anupward motion suicient to pull the tube upwardly inside the collar whichis held down by engagement of the cat whiskers with the inside wall ofthe pipe. The release of the collar enables spring S2 to expand withinthe spring chamber causing a downward motion of internal knife portions66 and outward motion of the external portions 68.

After the desired period of electrical contact has expired, theapparatus may be simply pulled from the pipe.

It is thus apparent that the apparatus of this invention provides asimple means by which good electrical conta-ct may be established withina pipe.

It is claimed:

1. A device for establishing electrical contact within a pipe whichcomprises a tubular support member, a plurality of contact elementsmovably mounted on said member for movement between a retracted positionin which said contact elements lie adjacent said support member and anextended position in which said contact elements extend outwardly ofsaid support member, a plate within said support member resting upon aportion of each of said contact elements and tending to move saidcontact elements toward said extended position by gravity when thedevice is in an upright position, a spring within said support memberacting against said plate to bias said conta-ct elements toward saidextended position, collar means on said support member movable between airst position in which it is adapted to extend over said contactelements and hold them in said retracted position against the bias ofsaid spring and plate and a second position in which said contactelements are free to move to said extended position, and releasablemeans for holding said collar means in said rst position.

2. The device of claim 1 in which said conta-ct elements are knifeelements each arranged for pivotal movement in a plane parallel to theaxis of the pipe to be contacted.

3. A device for establishing electrical contact within a pipe whichcomprises a tubular support member, a plurality of contact elementsmovably mounted on said member for movement between a retracted positionin which said contact elements lie adjacent said support member and anextended position in which said contact elements extend outwardly ofsaid support member, a plate within said support member resting upon aportion of each of said contact elements and tending to move saidcontact elements toward said extended position by gravity when thedevice is in an upright position, a spring within said support memberacting against said plate to bias said contact elements toward saidextended position, collar means on said support member movable between afirst position in which it is adapted to extend over said contactelements and hold them `in said retracted position against the bias ofsaid spring and plate and a second position in which said contactelements are free to move to said extended position, releasable meansfor holding said collar means in said first position, and drag meanscomprising a plurality of Wires attached to said collar means [andextending rearwardly of the device, said wires being adapted to contactthe interior wall of the pipe to be contacted with said contact elementsduring movement of said device.

4. A device for establishing electrical contact within a pipe whichcomprises a tubular support member, a plurality of lugs secured to theoutside of said .support member, said support member having a slottherein adjacent each said lug, a knife-like contact member pivotallysecured to each lug having an internal portion extending through theslot adjacent the lug into said support member and a portion external ofsaid support member, said contact members being pivotally mounted formovement between a retracted position in which said external portionsextend essentially parallel to the axis of said support member and anextended position in which said external portions extend outwardly fromsaid support member, a plate within said support member resting upon theinternal portions of said elements and tending to move said contactelements Itoward said extended position by gravity when the device is inan upright position, a spring within said support member acting againstsaid plate to bias said contact elements toward said extended position,collar means on said support member movable between a first position inwhich it is adapted to extend over the external portion of said contactelements and hold them in said retracted position against the bias ofsaid spring and plate and a second position in which said contactelements are free to pivot to said extended posit-ion, and releasablemeans for holding said collar means in said first position comprisingspring biased detent means arranged between said collar means and saidsupport member, and drag means comprising a plurality of wires attachedto said collar means and extending rearwardly of the device, said wiresbeing adapted to contact the interior wall of lthe pipe to be contactedwith said contact elements during movement of said device.

References Cited UNITED STATES PATENTS 1,034,963 '-8/1912 Boutte 166-1362,267,110 12/1941 Kinley et al 324-10 X 2,632,795 3/11953 YBoucher324-410 X 2,925,660 2/1960 Raulins 324-54 X WALTER L. CARLSON, PrimaryExaminer.

E. E. KUBASIEWICZ, Assistant Examiner,

1. A DEVICE FOR ESTABLISHING ELECTRICAL CONTACT WITHIN A PIPE WHICHCOMPRISES A TUBULAR SUPPORT MEMBER, A PLURALITY OF CONTACT ELEMENTSMOVABLY MOUNTED ON SAID MEMBER FOR MOVEMENT BETWEEN A RETRACTED POSITIONIN WHICH SAID CONTACT ELEMENTS LIES ADJACENT SAID SUPPORT MEMBER AND ANEXTENDED POSITION IN WHICH SAID CONTACT ELEMENTS EXTEND OUTWARDLY OFSAID SUPPORT MEMBER, A PLATE WITHIN SAID SUPPORT MEMBER RESTING UPON APORTION OF EACH OF SAID CONTACT ELEMENTS AND TENDING TO MOVE SAIDCONTACT ELEMENTS TOWARD SAID EXTENDED POSITION BY GRAVITY WHEN THEDEVICE IS IN AN UPRIGHT POSITION, A SPRING WITHIN SAID SUPPORT MEMBERACTING AGAINST SAID PLATE TO BIAS SAID CONTACT ELEMENTS TOWARD EXTENDEDPOSITION, COLLAR MEANS ON SAID SUPPORT MEMBER MOVABLE BETWEEN A FIRSTPOSITION IN WHICH IT IS ADAPTED TO EXTEND OVER SAID CONTACT ELEMENTS ANDHOLD THEM IN SAID RETRACTED POSITION AGAINST THE BIAS OF SAID SPRING ANDPLATE AND A SECOND POSITION IN WHICH SAID CONTACT ELEMENTS ARE FREE TOMOVE TO SAID EXTENDED POSITION, AND RELEASABLE MEANS FOR HOLDING SAIDCOLLAR MEANS IN SAID FIRST POSITION.